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Peter Anvin" , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, Colton Lewis Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Previously any PMU overflow interrupt that fired while a VCPU was loaded was recorded as a guest event whether it truly was or not. This resulted in nonsense perf recordings that did not honor perf_event_attr.exclude_guest and recorded guest IPs where it should have recorded host IPs. Rework the sampling logic to only record guest samples for events with exclude_guest =3D 0. This way any host-only events with exclude_guest set will never see unexpected guest samples. The behaviour of events with exclude_guest =3D 0 is unchanged. Note that events configured to sample both host and guest may still misattribute a PMI that arrived in the host as a guest event depending on KVM arch and vendor behavior. Signed-off-by: Colton Lewis --- arch/arm64/include/asm/perf_event.h | 4 ---- arch/arm64/kernel/perf_callchain.c | 28 ---------------------------- arch/x86/events/core.c | 16 ++++------------ include/linux/perf_event.h | 21 +++++++++++++++++++-- kernel/events/core.c | 21 +++++++++++++++++---- 5 files changed, 40 insertions(+), 50 deletions(-) diff --git a/arch/arm64/include/asm/perf_event.h b/arch/arm64/include/asm/p= erf_event.h index 31a5584ed423..ee45b4e77347 100644 --- a/arch/arm64/include/asm/perf_event.h +++ b/arch/arm64/include/asm/perf_event.h @@ -10,10 +10,6 @@ #include =20 #ifdef CONFIG_PERF_EVENTS -struct pt_regs; -extern unsigned long perf_arch_instruction_pointer(struct pt_regs *regs); -extern unsigned long perf_arch_misc_flags(struct pt_regs *regs); -#define perf_arch_misc_flags(regs) perf_misc_flags(regs) #define perf_arch_bpf_user_pt_regs(regs) ®s->user_regs #endif =20 diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_ca= llchain.c index 01a9d08fc009..9b7f26b128b5 100644 --- a/arch/arm64/kernel/perf_callchain.c +++ b/arch/arm64/kernel/perf_callchain.c @@ -38,31 +38,3 @@ void perf_callchain_kernel(struct perf_callchain_entry_c= tx *entry, =20 arch_stack_walk(callchain_trace, entry, current, regs); } - -unsigned long perf_arch_instruction_pointer(struct pt_regs *regs) -{ - if (perf_guest_state()) - return perf_guest_get_ip(); - - return instruction_pointer(regs); -} - -unsigned long perf_arch_misc_flags(struct pt_regs *regs) -{ - unsigned int guest_state =3D perf_guest_state(); - int misc =3D 0; - - if (guest_state) { - if (guest_state & PERF_GUEST_USER) - misc |=3D PERF_RECORD_MISC_GUEST_USER; - else - misc |=3D PERF_RECORD_MISC_GUEST_KERNEL; - } else { - if (user_mode(regs)) - misc |=3D PERF_RECORD_MISC_USER; - else - misc |=3D PERF_RECORD_MISC_KERNEL; - } - - return misc; -} diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index d51e5d24802b..3c5f512d2bcf 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2942,9 +2942,6 @@ static unsigned long code_segment_base(struct pt_regs= *regs) =20 unsigned long perf_arch_instruction_pointer(struct pt_regs *regs) { - if (perf_guest_state()) - return perf_guest_get_ip(); - return regs->ip + code_segment_base(regs); } =20 @@ -2971,17 +2968,12 @@ unsigned long perf_arch_guest_misc_flags(struct pt_= regs *regs) =20 unsigned long perf_arch_misc_flags(struct pt_regs *regs) { - unsigned int guest_state =3D perf_guest_state(); unsigned long misc =3D common_misc_flags(regs); =20 - if (guest_state) { - misc |=3D perf_arch_guest_misc_flags(regs); - } else { - if (user_mode(regs)) - misc |=3D PERF_RECORD_MISC_USER; - else - misc |=3D PERF_RECORD_MISC_KERNEL; - } + if (user_mode(regs)) + misc |=3D PERF_RECORD_MISC_USER; + else + misc |=3D PERF_RECORD_MISC_KERNEL; =20 return misc; } diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index d061e327ad54..968f3edd95e4 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1633,8 +1633,9 @@ extern void perf_tp_event(u16 event_type, u64 count, = void *record, struct task_struct *task); extern void perf_bp_event(struct perf_event *event, void *data); =20 -extern unsigned long perf_misc_flags(struct pt_regs *regs); -extern unsigned long perf_instruction_pointer(struct pt_regs *regs); +extern unsigned long perf_misc_flags(struct perf_event *event, struct pt_r= egs *regs); +extern unsigned long perf_instruction_pointer(struct perf_event *event, + struct pt_regs *regs); =20 #ifndef perf_arch_misc_flags # define perf_arch_misc_flags(regs) \ @@ -1645,6 +1646,22 @@ extern unsigned long perf_instruction_pointer(struct= pt_regs *regs); # define perf_arch_bpf_user_pt_regs(regs) regs #endif =20 +#ifndef perf_arch_guest_misc_flags +static inline unsigned long perf_arch_guest_misc_flags(struct pt_regs *reg= s) +{ + unsigned long guest_state =3D perf_guest_state(); + + if (guest_state & PERF_GUEST_USER) + return PERF_RECORD_MISC_GUEST_USER; + + if (guest_state & PERF_GUEST_ACTIVE) + return PERF_RECORD_MISC_GUEST_KERNEL; + + return 0; +} +# define perf_arch_guest_misc_flags(regs) perf_arch_guest_misc_flags(regs) +#endif + static inline bool has_branch_stack(struct perf_event *event) { return event->attr.sample_type & PERF_SAMPLE_BRANCH_STACK; diff --git a/kernel/events/core.c b/kernel/events/core.c index eeabbf791a8c..c5e57c024d9a 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6921,13 +6921,26 @@ void perf_unregister_guest_info_callbacks(struct pe= rf_guest_info_callbacks *cbs) EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks); #endif =20 -unsigned long perf_misc_flags(struct pt_regs *regs) +static bool should_sample_guest(struct perf_event *event) { + return !event->attr.exclude_guest && perf_guest_state(); +} + +unsigned long perf_misc_flags(struct perf_event *event, + struct pt_regs *regs) +{ + if (should_sample_guest(event)) + return perf_arch_guest_misc_flags(regs); + return perf_arch_misc_flags(regs); } =20 -unsigned long perf_instruction_pointer(struct pt_regs *regs) +unsigned long perf_instruction_pointer(struct perf_event *event, + struct pt_regs *regs) { + if (should_sample_guest(event)) + return perf_guest_get_ip(); + return perf_arch_instruction_pointer(regs); } =20 @@ -7743,7 +7756,7 @@ void perf_prepare_sample(struct perf_sample_data *dat= a, __perf_event_header__init_id(data, event, filtered_sample_type); =20 if (filtered_sample_type & PERF_SAMPLE_IP) { - data->ip =3D perf_instruction_pointer(regs); + data->ip =3D perf_instruction_pointer(event, regs); data->sample_flags |=3D PERF_SAMPLE_IP; } =20 @@ -7907,7 +7920,7 @@ void perf_prepare_header(struct perf_event_header *he= ader, { header->type =3D PERF_RECORD_SAMPLE; header->size =3D perf_sample_data_size(data, event); - header->misc =3D perf_misc_flags(regs); + header->misc =3D perf_misc_flags(event, regs); =20 /* * If you're adding more sample types here, you likely need to do --=20 2.46.0.662.g92d0881bb0-goog